package test;

/**
 * @author why
 * @data 2021/8/31
 */
public class test2 {
    public void quickSort(int[] arr, int l, int r) {
        if (l < r) {
            int[] p = partition(arr, l, r);
            quickSort(arr, l, p[0] - 1);
            quickSort(arr, p[1] + 1, r);
        }
    }

    public int[] partition(int[] arr, int l, int r) {
        int less = l - 1;
        int more = r;
        while (l < more) {
            if (arr[l] < arr[r]) {
                swap(arr, ++less, l++);
            } else if (arr[l] > arr[r]) {
                swap(arr, --more, l);
            } else {
                l++;
            }
        }
        swap(arr,more,r);
        return new int[]{less + 1, more};
    }

    public void swap(int[] arr, int i, int j) {
        int tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }
}
